Genetic diversity, allelic variation and marker trait associations in gamma irradiated mutants of rice (Oryza sativa L.)

Abstract

Purpose

Rice is a prime staple crop for more than half of the world population. Improved White Ponni (IWP) is a premium quality grain rice variety that is fetching a good price and is increasingly popular among the consumers of Tamil Nadu. Tall plant stature of IWP makes them susceptible to lodging and medium duration are two undesirable traits in the variety increases yield losses in the field and also productivity. In this context, we aimed to generate a large mutant population of IWP irradiated with various doses of gamma irradiation to recover putative mutants for semi-dwarfism and earliness.

Materials and methods

Totally, 34 putative mutants (22 early, 11 semi-dwarf and early and 1 Narrow-leaf dwarf mutant) were phenotyped for nine morphological traits and genotyped using 34 microsatellite markers linked to a trait of interest of earliness and semi-dwarfism. Trait variability, allelic variations, genetic structure and marker-trait associations in gamma-irradiated putative mutants of Improved White Ponni (IWP) rice were investigated in this study.

Results

The hierarchical clustering of morphological data produced five clusters with a dissimilarity coefficient of 1.39. A minimum dissimilarity coefficient of 0.23 was observed between the mutants IWPM9 and IWPM20 and a maximum dissimilarity coefficient of 2.55 was observed between IWPM1 and IWPM25. In cluster analysis with molecular marker data, five clusters with a similarity coefficient of 0.67 were observed. The mutant IWPM29 exhibited the most divergence from the wild type at the genotype level. The first principal component explained 50.99% of the total variability and the majority of the traits were contributed positively. The single-marker analysis revealed the strong association of SSR marker RM3912 with the traits plant height, panicle length and number of grains per panicle with an R² value of 0.235, 0.235 and 0.250 respectively.

Conclusions

The study identified semi-dwarf and short-duration rice mutants of IWP that can be utilized as potential breeding stocks. The trait-linked SSR markers can improve selection cycles in advanced breeding programs.

Keywords:

• Gamma radiation
• rice
• microsatellite
• single marker analysis

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

We extend our gratitude and sincere thanks to the Bhabha Atomic Research Centre of the Board of Research in Nuclear Sciences (BRNS), Department of Atomic Energy, Government of India, Mumbai for the financial assistance offered for this research.

Notes on contributors

S. Ramchander

Dr. S. Ramchander recently completed his Post-Doctoral fellowship from IRRI South Asia Hub, ICRISAT, Hyderabad. Dr. RS has published more than 35 research paper in high-impact and NAAS-rated peer-reviewed journals and participated in various national and international level conferences and symposiums. He is having nearly ten years of experience in rice breeding. His area of research interests is molecular breeding, quality breeding, bio-fortification, mutation breeding and genomics.

M. T. Andrew Peter Leon

Dr. M. T. Andrew Peter Leon recently completed his Ph.D. degree from Agricultural College and Research Institute, Killikulam, Tamil Nadu Agricultural University. He has published his research work in high-impact peer-reviewed journals.

J. Souframanien

Dr. J. Souframanien is currently working as a Scientist at Bhabha Atomic Research Centre, Nuclear Agriculture and Bio-technology Division, Mumbai. He has published more than 90 research articles in high-impact peer-reviewed journals. He has expertise in mutation breeding, trait mapping and functional genomics.

M. Arumugam Pillai

Dr. M. Arumugam Pillai is currently working as a Professor and Head in the Faculty of Plant Breeding and Genetics at Tamil Nadu Agricultural University (TNAU) in India. Dr. MAP has published a number of papers in preferred journals and chapters in books, and participated several international and national conferences and presented various academic as well as research-based papers. His areas of interests are molecular breeding, mutation breeding and molecular physiology. Number of scholars has completed research and many more are pursuing Post graduate and Ph.D. under his supervision.